How popular is Karlens?

Karlens is a rare given name for males. Karlens is also a unique surname for both adults and children. (2000 U.S. Demographics)

Which version is better?

with its source form and related boy names. Karson(#293 in recent rankings), Karl(#1082), Kale(#1100), Karlos and Karlton are the prominent alternative forms of Karlens (not ranked) appearing in the Top 2000. Other forms, like Karlan, are uncommon. These forms of Karlens were popular as birth names 55 years ago (usage of 0.1%) and are somewhat less conventional today (usage 0.1%, ▼25.5%), with the form Karl becoming somewhat dated. Karl has historically been preferred by parents, though Karson has become popular as well. (2015 U.S. SSA Records)